Patent GB-191006654-A (GB)
Title: Improvements in Automatic Telephone Exchanges.
Filed: 1910-03-16
Granted: 1911-03-02
Abstract: 6654. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. March 16. Automatic exchange systems ; metering systems.- In a metering system in which the register is operated at the close of the conversation, the deenergizing of a line relay at the connector, when either subscriber replaces his receiver, produces a preparatory change of connexions whereby the register is operated, and a further change of connexions at the first selector results in the release of the selectors and connector. The invention is described as applied to a system in which the register is included in the test lead of the subscriber's preliminary selector and is actuated when a change in resistance in this lead is produced by a relay in the first selector. Preliminary selector. The removal of the calling subscriber's receiver energizes his line relay R<33>, which closes at r<1> the circuit of the actuating- magnet D<33> through an interrupter U<0>. As soon as the selector moves, the contact i<1> moves into the position shown, and the contact i<2> is opened, thus rendering the subscriber busy to other calls. When the wiper o<3> engages the test lead of an idle first selector, current flows from the battery over a contact r<3>, winding 2 of the out-off relay TR<33>, winding 1 and register ZR in parallel, lead c<1>, resistances w<1>, w<2>, contact n<1> of the release magnet N, arm s<4>, the upper winding of a relay P, and arm s<3> to earth. The relay TR<33> is thus energized, and (1) connects the calling-lines over the contacts t<1>, t<2> to the relays X, A, B of the first selector, at the same time disconnecting the line relay R<33>; and (2) closes contact t<3>, thus short-circuiting the high-resistance winding 2, and connecting the battery directly over contacts i<1>, t<3> to the winding 1. The change of potential in the lead c<1> produced by cutting out the winding 2 marks the lead c<1> as engaged to other preliminary selectors. The resistances w<1>, w<2> prevent the excitation of the register ZR at this stage. Side-switch construction. A construction of the side-switch for the selectors and connector is shown in Fig. 4. The switch shaft is controlled by the doubletoothed escapement bar 1 0 3 and spring 100 in the usual way, and is returned to zero by the armature 106 of a separate release magnet N. A contact l<0> in the circuit of the magnet N is closed on the first movement of the side-switch. The side-switch used in the first selector has nine arms and seven positions. First selector. The increase in current in the test-lead circuit, produced by cutting-out the winding 2 of the relay TR<33>, energizes the relay P, which completes a circuit for the side-switch magnet S over the arms s<11>, s<6> in their first position to the interrupter U and battery G. The magnet S moves the side-switch into its second position, in which the test lead c<1> is earthed over the arm S', and the calling station is connected over the arms s<1>, s<2> to the relays A, B, X. The subscriber's impulse-sender is arranged to earth the b-line before and during the successive interruptions of the a-line, so that when the subscriber turns his impulse-sender, the earthing of the b-line upsets the balance of the differential relay X, which closes a contact x so that current flows over this contact and then divides, part passing over the relay B to earth and part through the winding of the relay X to earth at the sub-station, as described in Specification 9634/10. The relays B, X are thus energized independently of the a-line, so that they are unaffected by the subsequent interruptions of the a-line. The relay B opens at d' the circuit of the release magnets M, N, so that if the subscriber replaces his receiver at this stage, the de-energizing of the relay B effects the release of the selector. The relay X also closes a contact x<1> so that the first set of selecting-impulses, sent by interrupting the a-line, are repeated by the relay A over the contact a', arms s<6>, s<11> in their second position, to the vertical magnet H. The closing of contact x<1> also prepares a circuit for the magnet S, which is completed at k on the first movement of the selector. When the impulse-sender returns to zero, the relay X is de-energized and opens at x<1> the circuit of the magnet S, so that the side-switch moves into its third position, in which the circuit of the rotary magnet D is completed by the arm s<3>, and the test magnet P is connected to the test wiper o<6> by the arm s<4>. When an idle second selector has been found, current flows from the battery over a contact d<1> of the relay B<1>, Fig. 2, arm s<12>, lead c<2>, and both windings of the relay P to earth. The relay P opens the circuit through the arms s<11>, s<6> over which the magnet S was energized in the third position of the side-switch, so that this moves into its fourth position, disconnecting the rotary magnet D, and directly earthing the lowresistance upper winding of the relay P. The arm s<5> completes another circuit for the magnet S through the interrupter U, so that the side-switch moves at once into its fifth, or conversation, position. Second selector. In the fourth and fifth positions of the side-switch of the first selector, the calling station is connected through to the relays A<1>, B<1>, X<1>, the relay B<1> disconnecting the battery from the test lead c<2>. The second set of selecting-impulses are repeated by the relays A', X<1>, as before, to t h e vertical magnet H<1>, and when the impulse-sender returns to zero, the relay X<1> opens the circuit of the magnet S<1>, so that the side-switch moves into its second position, in which the circuit of the rotary magnet D<1> is closed by the arm s<11>. When the wiper o<9> reaches the contact of an idle connector, the relay P<1> is energized and opens the circuit of the magnet S<1>, so that the side-switch moves into its third position, and then at once into its fourth, or conversation, position. Connector. In the third and fourth positions of the side-switch of the second selector, the calling station is connected through to the relays A<2>, B<2>, X<2>, the relay B<2> disconnecting the battery from the test lead c<3>. The third set of selecting-impulses are repeated, by the relays A<2>, X<2>, as before, to the vertical magnet H', and when the impulsesender returns to zero, the relay X<2> opens the circuit of the magnet S<2>, so that the side-switch moves into its second position, in which the rotary magnet D<2> is substituted for the magnet H<2>. The final set of selecting - impulses are thus repeated by the relays A<2>, X<2> to the magnet D', which moves the wipers on to the contacts of the desired line. The magnet S<2> is again de-energized so that the side-switch moves into its third position. Busy test. The test relay Y, which was energized in the second position of the arm s<18> so as to prevent the closing of a release circuit over the lead c<3> when the arm s<19> moved into its third position, is thus connected by the arm s<17> to the test wiper o<12>. If the required subscriber is engaged, his test lead is interrupted (as at i<2>, Fig. 1) if he is himself a calling subscriber, or it is directly earthed (as at s<17>, Fig. 3) if he has been called bv some other subscriber. If the connexion cannot be obtained, the relay Y is thus deenergized, and by closing contact y<0> connects the battery over the arm s<19> to the test lead c<3>, thus bringing about the release of the first and second selectors, as described later. In this position of the side switch of the connector, the release of the second selector breaks the circuit of the relay B', which completes the circuit of the release magnets M', N' through the arm s<21>. Supply and control of ringing-current. If the required subscriber is disengaged, the relay Y remains energized over a circuit which includes the windings 1, 2 of the called subscriber's cut off relay TR<55>. The contact y' thus remains closed so that an impulse from the interrupter U passes through the magnet S<2>, which thus moves the side-switch into its fourth position, in which the arm s<17> directly earths the test lead c<55>, and opens the circuit of the test relay Y, which closes at y<0> a circuit through the ringing-relay L and arm s<23>. The ringing-generator RQ is thus bridged across the called line, and this first call lasts until a slowly moving interrupter U<1> sends a further impulse through the magnet S<2>, whereby the sideswitch is moved into its fifth position, in which the ringing-relay is intermittently earthed through an interrupter Co. In the fifth position of the arm s<16> the relay Y is connected to the called subscriber's b-line, so that when the subscriber replies, current flows from the battery through an inductance D<r>, arm s<18>, called sub-station, arm s<16>, and relay Y to earth. The closing of contact y' sends a further impulse through the magnet S<2>, so that the sideswitch moves into its sixth, or conversation, position. Microphone current for the called subscriber flows over the inductance D<r> and relay Y, and for the calling subscriber over the relays A<2>, B<2>, X<2>. Metering arrangements and release. When the calling subscriber or the called subscriber hangs up his receiver, the relay B' or Y, respectively, is deenergized, so that a further impulse from the interrupter U passes over contact d<2> or y to the magnet S<2>, thus moving the side-switch into its seventh position, in which the arm s<19> connects the battery and relay Q<2> to the test lead c<3>, thereby energizing the relays Q<2>, and P', Fig. 2. The relay Q<2> brings the magnet S<2> into a holding-on circuit, whilst the relay P' closes a circuit through a relay Q<1>, test lead c<2>, and relay P, Fig. 1. The relay Q<1> brings the magnet S<1> into a holding-on circuit, whilst the relay P connects the magnet S over the arms s<11>, s<6> to the interrupter U, thus moving the side-switch of the fir